Analyzing a particular wireless signal based on characteristics of other wireless signals

ABSTRACT

The present disclosure discloses a system and method for classifying Wi-Fi signals from Fourier transform samples. Generally, classifying Wi-Fi signals from Fourier transform samples includes: collecting and dividing Fourier transform samples into frequency blocks; determining the bandwidth for the Fourier transform sample; and determining whether the Fourier transform sample corresponds to a narrowband signal. Further, if a determination is made that the Fourier transform sample does not correspond to a narrowband signal, channel utilization is calculated based on a determination that the FFT sample corresponds to a Wi-Fi signal. If it is determined that the Fourier transform sample corresponds to a narrowband signal, then a determination is made that the FFT sample corresponds to a Wi-Fi signal based on certain criteria. The certain criteria may include one or more of a slope value, a number of sub-peak bins, an analysis of adjacent channels, characteristic matching, or other criteria.

PRIORITY APPLICATION INFORMATION

This application is a continuation of U.S. application Ser. No.14/097,198 filed Dec. 4, 2013, the contents of which are incorporatedherein by reference.

FIELD

The present disclosure relates to detecting and classifying Wi-Fisignatures from Fourier Transform samples, e.g., Fast Fourier Transform(FFT) samples. In particular, the present disclosure relates toclassifying Wi-Fi signals from Fourier transform samples to minimizefalse detections.

BACKGROUND

Wireless digital networks provide users secure and cost-effective accessto resources. Such wireless digital networks typically have a pluralityof access points (AP) located throughout a designated area, by which theusers can access the resources they desire. Wi-Fi networks operating inaccordance with IEEE 802.11 standards are examples of such networks. Thefrequencies used by these networks are shared. They are shared not onlyamong the wireless digital networks themselves, but also with othernon-network devices. These shared frequencies face intermittent andcontinuous interference received from other non-network devices,including radio-frequency devices, such as microwave ovens, wirelessvideo streaming devices, cordless telephones, and the like, as well asother adjacent wireless networking devices. Unfortunately, the effectsof these types of interfering devices can vary. As an example, simplyreplacing or adding a microwave oven in a particular area where aparticular wireless digital network is operating can dramatically alterthe interference levels present within that particular wireless digitalnetwork.

To identify the sources of interference that obstruct operation of awireless digital network, various types of test equipment andfunctionalities are used, for example, spectrum analyzers. Althoughsophisticated spectrum analyzers exist, which include receivers that maybe calibrated to display and measure signals over a wide range offrequencies and amplitudes, such sophisticated devices are costly andoften not used for continuous monitoring and management of wirelessdigital networks. Wireless digital networks contain access points (AP)and wireless client devices, both examples of narrowband network (radio)devices with spectrum data collection functionality.

A radio has the capability to receive Wi-Fi packets as well as non-Wi-Fiinterference, which is received as Fourier transform samples. Not allWi-Fi is received as Wi-Fi signals and not all non-Wi-Fi are received asFourier transform samples. False detection may happen, for example,Wi-Fi packets may be received as FFT samples. Often, a majority of falsedetections of interferers are caused by the existence of Wi-Fi frames onthe air that the radio cannot decode. For example, an 11n radio will notbe able to decode wireless frames in compliance with IEEE 802.11acstandard and a 20 MHz radio will not be able to decode 40 MHz frames.Similarly, a radio that does not support optional formats such as STBC,LDPC, and Greenfield will not be able to decode these frames. Inaddition, frames on adjacent channels may also simply appear as “energy”on the channel. Since Wi-Fi frames may have large enough duration andthe fixed FFT signature, these are highly likely to be classified as afixed frequency or a frequency hopping interferer. Therefore, methodsare required to filter out the FFTs that are generated by Wi-Fi framesin order to minimize false detections. In addition, the accurateclassification of FFT signatures (non-Wi-Fi interferer vs. Wi-Fi) willalso improve the accuracy of the channel utilization or duty cyclecalculations.

Therefore, it is desirable to have enhanced ways for accuratelyclassifying interferers as well as minimize the number of falsedetections.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be best understood by referring to thefollowing description and accompanying drawings that are used toillustrate embodiments of the present disclosure.

FIG. 1 is a block diagram illustrating an example network environmentaccording to embodiments of the present disclosure.

FIG. 2 is a block diagram illustrating an example network deviceaccording to embodiments of the present disclosure.

FIG. 3 is a block diagram illustrating an example Wi-Fi signaturedetection application according to some embodiments of the presentdisclosure. The application is stored on a memory of the example networkdevice or system.

FIG. 4 illustrates an example process for detecting Wi-Fi signals fromFFT samples according to embodiments of the present disclosure.

FIG. 5 illustrates an example process for detecting a Wi-Fi signal basedon slope values according to embodiments of the present disclosure.

FIG. 6 illustrates an example process for determining signal type basedon a number of sub-peak frequency bins according to embodiments of thepresent disclosure.

FIG. 7A illustrates an example process for determining a number ofsub-peak bins according to embodiments of the present disclosure.

FIG. 7B illustrates an example process for a number of sub-peak binsaccording to other embodiments of the present disclosure.

FIG. 7C illustrates an example process for a number of sub-peak binsaccording to yet other embodiments of the present disclosure.

FIG. 8 illustrates an example process for estimating a burst sizeaccording to embodiments of the present disclosure.

FIG. 9 illustrates an example process for detecting Wi-Fi signals basedon estimation for adjacent channels according to embodiments of thepresent disclosure.

FIG. 10 illustrates an example process for classifying Wi-Fi signalsbased on characteristic matching according to embodiments of the presentdisclosure.

FIG. 11 illustrates an example process for classifying Wi-Fi signalsaccording to other embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following description, several specific details are presented toprovide a thorough understanding. While the context of the disclosure isdirected to task processing and resource sharing in a distributedwireless system, one skilled in the relevant art will recognize,however, that the concepts and techniques disclosed herein can bepracticed without one or more of the specific details, or in combinationwith other components, etc. In other instances, well-knownimplementations or operations are not shown or described in details toavoid obscuring aspects of various examples disclosed herein. It shouldbe understood that this disclosure covers all modifications,equivalents, and alternatives falling within the spirit and scope of thepresent disclosure.

Overview

Some embodiments of the present disclosure relates to classifying Wi-Fisignals from Fourier transform samples. Generally, classifying Wi-Fisignals from Fourier transform samples includes: collecting and dividingFourier transform samples into frequency blocks; determining thebandwidth for the Fourier transform sample; and determining whether theFourier transform sample corresponds to a narrowband signal. Further, ifa determination is made that the Fourier transform sample does notcorrespond to a narrowband signal, channel utilization is calculatedbased on a determination that the FFT sample corresponds to a Wi-Fisignal. If it is determined that the Fourier transform samplecorresponds to a narrowband signal, then a determination is made thatthe FFT sample corresponds to a Wi-Fi signal based on certain criteria.The certain criteria may include one or more of a slope value, a numberof sub-peak bins, an analysis of adjacent channels, characteristicmatching, or other criteria.

In some embodiments, classifying Wi-Fi signals from Fourier transformsamples is based on slope values. In such embodiments, the detecting andclassifying includes: determining, for each of a plurality of frequencybins in a Fourier Transform sample a corresponding signal strength, theFourier Transform sample corresponding to a wireless signal as detectedat a first time period; identifying a first frequency bin, from theplurality of frequency bins, with a first signal strength, the firstsignal strength being a highest signal strength in the signal strengthscorresponding to each of the plurality of frequency bins; determining adecrease in signal strength between (a) the first signal strengthcorresponding to the first bin and (b) a second signal strengthcorresponding to a second bin in the plurality of bins; and based atleast on the decrease in signal strength and a frequency differencebetween the first bin and the second bin, classifying the FourierTransform sample.

In some embodiments, classifying Wi-Fi signals from Fourier transformsamples is based on a number of sub-peak bins. In such embodiments, theclassifying includes: determining, for each of a plurality of frequencybins in a Fourier Transform sample a corresponding signal strength, theFourier Transform sample corresponding to a wireless signal as detectedat a first time period; identifying a first frequency bin, from theplurality of frequency bins, with a first signal strength, the firstsignal strength being a highest signal strength in the signal strengthscorresponding to each of the plurality of frequency bins; identifying asubset of the plurality of frequency bins, each particular bin in thesubset of frequency bins corresponding to signal strengths that is (a)lower than the first signal strength, (b) higher than at least thesignal strength for n consecutive frequency bins in the plurality offrequency bins preceding the particular bin, and (c) higher than atleast the signal strength for m consecutive frequency bins in theplurality of frequency bins subsequent to the particular bin; and basedon a number of frequency bins in the subset of frequency bins,classifying the Fourier Transform sample. In some embodiments, thesub-peak frequency bin is any frequency bin corresponding to a signalstrengths that is (a) lower than the first signal strength, (b) higherthan at least the signal strength for n consecutive frequency bins inthe plurality of frequency bins preceding the particular bin, and (c)higher than at least the signal strength for m consecutive frequencybins in the plurality of frequency bins subsequent to the particularbin. The detecting and classifying further includes determining a signaltype for the signal based at least on the number of sub-peak frequencybins within the particular number of frequency bins from the peakfrequency bin.

In some embodiments, classifying Wi-Fi signals from Fourier transformsamples is based on analysis of adjacent channels. In such embodiments,the classifying includes: detecting a plurality of wireless signals on acorresponding plurality of frequency channels; classifying each of theplurality of wireless signals as Wi-Fi signals or non-Wi-Fi signals; andanalyzing information for the wireless signals from the plurality ofwireless signals that were classified as Wi-Fi signals to identify atleast two of the wireless signals detected on two corresponding channelsas a portion of a same Wi-Fi transmission from a same source device. Insome embodiments, the wireless signal is near an edge of the secondradio frequency channel shared with the first radio frequency channel.

In some embodiments, detecting and classifying Wi-Fi signals from FFTsamples is based on characteristic matching. In such embodiments, thedetecting and classifying includes: detecting a first wireless signal;determining that at least a portion of the characteristics associatedwith the first wireless signal matches that of a second wireless signalthat was previously classified as a Wi-Fi signal; and classifying thefirst wireless signal as a Wi-Fi signal based at least on thedetermination that at least a portion of the characteristics associatedwith the first wireless signal matches the second wireless signal.

In some embodiments, detecting and classifying Wi-Fi signals from FFTsamples is based on other combination criteria. In such embodiments, thedetecting and classifying includes: detecting a first wireless signalcorresponding to a frequency band; identifying different subsections ofthe frequency band and corresponding component wireless signals in thedifferent subsections, the component wireless signals forming the firstwireless signal; selecting a plurality of combinations of componentwireless signals using the different subsections; classifying theplurality of combinations of component wireless signals as Wi-Fi signalsor non-Wi-Fi signals; and determining that the first wireless signal isnon-Wi-Fi in response to determining that none of the plurality ofcombinations of component wireless signals has been classified as Wi-Fisignals.

Computing Environment

FIG. 1 shows an example digital network environment 199 according toembodiments of the present disclosure. FIG. 1 includes at least one ormore network controller (such as controller 100), one or more accesspoints (such as access point 160), one or more client devices (such asclient 170), a layer 2 or layer 3 network 110, a routing device (such asrouter 120), a gateway 130, Internet 140, and one or more web servers(such as web server A 150, web server B 155, and web server C 158), etc.The components of the digital network environment 199 arecommunicatively coupled to each other. In some embodiments, the digitalnetwork environment 199 may include other components not shown in FIG. 1such as an email server, a cloud-based storage device, etc. It isintended that any of the servers shown may represent an email serverinstead as illustrated with email functionalities and any of the networkdevices may serve as a cloud-based storage device. The network 140 maybe implemented within a cloud environment.

The controller 100 is a hardware device and/or software module thatprovide network managements, which include but are not limited to,controlling, planning, allocating, deploying, coordinating, andmonitoring the resources of a network, network planning, frequencyallocation, predetermined traffic routing to support load balancing,cryptographic key distribution authorization, configuration management,fault management, security management, performance management, bandwidthmanagement, route analytics and accounting management, etc. In someembodiments, the controller 100 is an optional component in the digitalnetwork environment 199.

Moreover, assuming that a number of access points, such as access point160, are interconnected with the network controller 100. Each accesspoint 160 may be interconnected with zero or more client devices viaeither a wired interface or a wireless interface. In this example, forillustration purposes only, assuming that the client 170 is associatedwith the access point 160 via a wireless link. An access point 160generally refers to a network device that allows wireless clients toconnect to a wired network. Access points 160 usually connect to acontroller 100 via a wired network or can be a part of a controller 100in itself. For example, the access point 160 is connected to thecontroller 100 via an optional L2/L3 network 110B.

Wired interfaces typically include IEEE 802.3 Ethernet interfaces, usedfor wired connections to other network devices such as switches, or to acontroller. Wireless interfaces may be WiMAX, 3G, 4G, and/or IEEE 802.11wireless interfaces. In some embodiments, controllers and APs mayoperate under control of operating systems, with purpose-built programsproviding host controller and access point functionality.

Furthermore, the controller 100 can be connected to the router 120through zero or more hops in a layer 3 or layer 2 network (such as L2/L3Network 110A). The router 120 can forward traffic to and receive trafficfrom the Internet 140. The router 120 generally is a network device thatforwards data packets between different networks, and thus creating anoverlay internetwork. A router 120 is typically connected to two or moredata lines from different networks. When a data packet comes in one ofthe data lines, the router 120 reads the address information in thepacket to determine its destination. Then, using information in itsrouting table or routing policy, the router 120 directs the packet tothe next/different network. A data packet is typically forwarded fromone router 120 to another router 120 through the Internet 140 until thepacket gets to its destination.

The gateway 130 is a network device that passes network traffic fromlocal subnet to devices on other subnets. In some embodiments, thegateway 130 may be connected to a controller 100 or be a part of thecontroller 100 depending on the configuration of the controller 100. Insome embodiments, the gateway 130 is an optional component in thedigital network environment 199.

Web servers 150, 155, and 158 are hardware devices and/or softwaremodules that facilitate delivery of web content that can be accessedthrough the Internet 140. For example, the web server A 150 may beassigned an IP address of 1.1.1.1 and used to host a first Internetwebsite (e.g., www.yahoo.com); the web server B 155 may be assigned anIP address of 2.2.2.2 and used to host a second Internet website (e.g.,www.google.com); and, the web server C 158 may be assigned an IP addressof 3.3.3.3 and used to host a third Internet website (e.g.,www.facebook.com).

The client 170 may be a computing device that includes a memory and aprocessor, for example a laptop computer, a desktop computer, a tabletcomputer, a mobile telephone, a personal digital assistant (PDA), amobile email device, a portable game player, a portable music player, areader device, a television with one or more processors embedded thereinor coupled thereto or other electronic device capable of accessing anetwork. Although only one client 170 is illustrated in FIG. 1, aplurality of clients 170 can be included in FIG. 1.

Network Device for Wi-Fi Signature Detection Application

FIG. 2 is a block diagram illustrating an example network device system200 for detecting Wi-Fi signatures according to embodiments of thepresent disclosure. The network device 200 may be used as a networkswitch, a network router, a network controller, a network server, anaccess point, etc. Further, the network device 200 may serve as a nodein a distributed or a cloud computing environment.

According to embodiments of the present disclosure, network servicesprovided by the network device 200, solely or in combination with otherwireless network devices, include, but are not limited to, an Instituteof Electrical and Electronics Engineers (IEEE) 802.1x authentication toan internal and/or external Remote Authentication Dial-In User Service(RADIUS) server; an MAC authentication to an internal and/or externalRADIUS server; a built-in Dynamic Host Configuration Protocol (DHCP)service to assign wireless client devices IP addresses; an internalsecured management interface; Layer-3 forwarding; Network AddressTranslation (NAT) service between the wireless network and a wirednetwork coupled to the network device; an internal and/or externalcaptive portal; an external management system for managing the networkdevices in the wireless network; etc. In some embodiments, the networkdevice or system 200 may serve as a node in a distributed or a cloudcomputing environment.

In some embodiments, the network device 200 includes a network interface202 capable of communicating to a wired network, a processor 204, amemory 206 and a storage device 210. The components of the networkdevice 200 are communicatively coupled to each other.

The network interface 202 can be any communication interface, whichincludes but is not limited to, a modem, token ring interface, Ethernetinterface, wireless IEEE 802.11 interface (e.g., IEEE 802.11n, IEEE802.11ac, etc.), cellular wireless interface, satellite transmissioninterface, or any other interface for coupling network devices. In someembodiments, the network interface 202 may be software-defined andprogrammable, for example, via an Application Programming Interface(API), and thus allowing for remote control of the network device 200.

The processor 204 includes an arithmetic logic unit, a microprocessor, ageneral purpose controller or some other processor array to performcomputations and provide electronic display signals to a display device.Processor 204 processes data signals and may include various computingarchitectures including a complex instruction set computer (CISC)architecture, a reduced instruction set computer (RISC) architecture, oran architecture implementing a combination of instruction sets. AlthoughFIG. 2 includes a single processor 204, multiple processors 204 may beincluded. Other processors, operating systems, sensors, displays andphysical configurations are possible. In some embodiments, the processor204 includes a networking processor core that is capable of processingnetwork data traffic.

The memory 206 stores instructions and/or data that may be executed bythe processor 204. The instructions and/or data may include code forperforming the techniques described herein. The memory 206 may be adynamic random access memory (DRAM) device, a static random accessmemory (SRAM) device, flash memory or some other memory device. In someembodiments, the memory 206 also includes a non-volatile memory orsimilar permanent storage device and media including a hard disk drive,a floppy disk drive, a CD-ROM device, a DVD-ROM device, a DVD-RAMdevice, a DVD-RW device, a flash memory device, or some other massstorage device for storing information on a more permanent basis.

In some embodiments, the memory 206 stores a Wi-Fi signature detectionapplication 208. The Wi-Fi signature detection application 208 can bethe code and routines that, when executed by processor 204, cause thenetwork device 200 to implement detecting and classifying Wi-Fisignatures from FFT samples. In some embodiments, a node can be anaccess point 160. In some other embodiments, a node can be a controller100, a router 120, a gateway 130, a switch or any other network device.In some embodiments, the Wi-Fi signature detection application 208 canbe located in an access point 160. In some other embodiments, the Wi-Fisignature detection application 208 can be located in a controller 100,a router 120, a gateway 130, a switch or any other network device. Insome embodiments, the Wi-Fi signature detection application 208 can beimplemented using hardware including a Field-Programmable Gate Array(FPGA) or an Application-Specific Integrated Circuit (ASIC. In someother embodiments, the Wi-Fi signature detection application 208 can beimplemented using a combination of hardware and software. In someembodiments, the Wi-Fi signature detection application 208 may be storedin a combination of the network devices, or in one of the networkdevices. The Wi-Fi signature detection application 208 is describedbelow in more detail with reference to FIGS. 3-11.

The storage device 210 can be a non-transitory memory that stores datafor providing the functionality described herein. The storage device 210may be a dynamic random access memory (DRAM) device, a static randomaccess memory (SRAM) device, flash memory or some other memory devices.In some embodiments, the storage device 210 also includes a non-volatilememory or similar permanent storage device and media including a harddisk drive, a floppy disk drive, a CD-ROM device, a DVD-ROM device, aDVD-RAM device, a DVD-RW device, a flash memory device, or some othermass storage device for storing information on a more permanent basis.

Wi-Fi Signature Detection Application

FIG. 3 illustrates an example Wi-Fi signature detection application 208stored on a memory 206 according to embodiments of the presentdisclosure. In some embodiments, the Wi-Fi signature detectionapplication 208 includes a communication module 302, a banddetermination module 304, a slope calculation module 306, a sub-peak binestimation module 308, a burst measurement module 310, a classificationmodule 312, a characteristic matching module 314, and a combinationmodule 316.

The Wi-Fi signature detection application 208 can be software includingroutines for detecting and classifying Wi-Fi signals from Fouriertransform samples based on certain criteria. In some embodiments, theWi-Fi signature detection application 208 can be a set of instructionsexecutable by the processor 204 to provide the functionality describedherein. In some other embodiments, the Wi-Fi signature detectionapplication 208 can be stored in the memory 206 and can be accessibleand executable by the processor 204.

A Fourier transform converts time (or space) to frequency and viceversa. A Fast Fourier Transform, or FFT, is a kind of Fourier transformmethod for computing the frequency spectrum of a time-varying inputsignal. This line chart shows the power level of a signal on thechannels or frequencies monitored by a spectrum monitor radio. Table 1below illustrates an example FFT signal strength levels corresponding todifferent frequency bins.

TABLE 1 Frequency Bin No. Signal Strength 0 −95 dBm 1 −90 dBm 2 −80 dBm3 −72 dBm 4 −75 dBm 5 −70 dBm 6 −65 dBm 7 −50 dBm 8 −70 dBm 9 −75 dBm 10−80 dBm 11 −65 dBm 12 −75 dBm 13 −80 dBm 14 −90 dBm 15 −95 dBm

The Wi-Fi signature detection application 208 determines whether aFourier transform sample corresponds to a Wi-Fi signal based on certaincriteria. In some embodiments, the Wi-Fi signature detection application208 collects and divides Fourier transform samples, such as FFT samples,into frequency block and determines the bandwidth for the FFT sample. Ifthe Wi-Fi signature detection application 208 determines that the sampledoes not correspond to a narrowband signal, then it calculates channelutilization based on a determination that the FFT sample corresponds toa Wi-Fi signal. If the Wi-Fi signature detection application 208determines that the FFT sample corresponds to a narrowband signal, thenit determines that the FFT sample corresponds to a Wi-Fi signal based oncertain criteria.

Various modules included in the Wi-Fi signature detection application208 determines that the FFT sample corresponds to a Wi-Fi signal basedon various criteria. Examples of these various criteria are described inthe descriptions of the slope calculation module 306, the sub-peakestimation module 308, the classification module 312, the characteristicmatching module 314 and the combination module 316.

The communication module 302 can be software including routines forhandling communications between the Wi-Fi signature detectionapplication 208 and other components in the digital computingenvironment 199 (FIG. 1). In some embodiments, the communication module302 can be a set of instructions executable by the processor 204 toprovide the functionality described herein. In some other embodiments,the communication module 302 can be stored in the memory 206 of theWi-Fi signature detection application 208 and can be accessible andexecutable by the processor 204.

In some embodiments, the communication module 302 may be adapted forcooperation and communication with the processor 204 and othercomponents of the Wi-Fi signature detection application 208 such as thenetwork interface 202, the storage 210, etc.

In some embodiments, the communication module 302 sends and receivesdata to and from one or more of a client 170 (FIG. 1), an access point160 (FIG. 1) and other network devices via the network interface 202(FIG. 2), in the event of distributed functionalities. In someembodiments, the communication module 302 handles communications betweencomponents of the Wi-Fi signature detection application 208. In someembodiments, the communication module 302 receives data from othercomponents of the Wi-Fi signature detection application 208 and storesthe data in the storage device 210.

The band determination module 304 can be software including routines fordetermining whether an FFT sample corresponds to a Wi-Fi signal based oncertain criteria. In some embodiments, the band determination module 304can be a set of instructions executable by the processor 204 to providethe functionality described herein. In some other embodiments, the banddetermination module 304 can be stored in the memory 206 of the Wi-Fisignature detection application 208 and can be accessible and executableby the processor 204.

In some embodiments, the band determination module 304 collects anddivides FFT samples into frequency block and determines the bandwidthfor the FFT sample.

The slope calculation module 306 can be software including routines fordetermining whether the FFT sample corresponds to a Wi-Fi signal basedat least on the slope values. In some embodiments, the slope calculationmodule 306 can be a set of instructions executable by the processor 204to provide the functionality described herein. In some otherembodiments, the slope calculation module 306 can be stored in thememory 206 of the Wi-Fi signature detection application 208 and can beaccessible and executable by the processor 204.

In some embodiments, slope calculation module 306 determines whether theFourier transform sample corresponds to a Wi-Fi signal based on theslope values. The slope calculation module 306 identifies a peakfrequency bin for an FFT sample from a plurality of frequency binscorresponding to signal strength for a signal detected on a channel at aparticular time. In some embodiments, the peak frequency bin correspondsto a peak in signal strength. For instance, in the example illustratedin Table 2, the peak frequency bin is frequency bin No. 7, whichcorresponds to a signal strength level of −50 dBm. The slope calculationmodule 306 then determines a decrease in signal strength between (a) thefirst signal strength corresponding to the first bin and (b) a secondsignal strength corresponding to a second bin in the plurality of bins.

Specifically, in some embodiments, the slope calculation module 306 cancompute a set of slope values between the signal strength correspondingto the peak frequency bin and the signal strength for each of aplurality of frequency bins within a certain range from the peakfrequency bin. For example, in the example illustrated in Table 2, theslope calculation module 306 may calculate a slope value based on signalstrength levels corresponding to each of (i) bins 7 and 8, (ii) bins 7and 9, (iii) bins 7 and 10, (iv) bins 7 and 11, (v) bins 7 and 12, etc.Accordingly, the resulting slope values are: (i) 20, (ii) 25, (iii) 30,(iv) 15, (v) 25, etc. The slope calculation module 306 then compareseach of the slope values to a corresponding threshold value that isdependent on the number of the frequency bins between the peak frequencybin and the frequency bin corresponding to that slope. For example, theset of threshold values corresponding to (i) bins 7 and 8, (ii) bins 7and 9, (iii) bins 7 and 10, (iv) bins 7 and 11, (v) bins 7 and 12, maybe (i) 40, (ii) 35, (iii) 30, (iv) 25, (v) 20, etc. The slopecalculation module 306 then determines a number of satisfying slopevalues from the set of slope values. In some embodiments, the satisfyingslope values meet their corresponding thresholds, for example, the slopevalues corresponding to (iii) bins 7 and 10 (i.e., a slope value of 30),and (v) bins 7 and 12 (i.e., a slope value of 25) meet theircorresponding threshold values (i.e., 30 for bins 7 and 10, and 20 forbins 7 and 12). Finally, the slope calculation module 306 determineswhether the FFT sample corresponds to a Wi-Fi signal based at least onthe number of satisfying slope values. Here, for example, because only 2out of 5 slope values meet the threshold, the slope calculation module306 may determine that the FFT sample does not correspond to a Wi-Fisignal, but rather a narrow band interference signal.

In some embodiments, the slope calculation module 306 also determines aburst duration for the signal. In such embodiments, determining whetherthe FFT sample corresponds to a Wi-Fi signal may also be based on theburst duration exceeding a predetermined threshold value.

In some embodiments, the slope calculation module 306 also computes anaverage slope value of the slope values corresponding to the frequencybins preceding the peak frequency bin. In such embodiments, determiningwhether the FFT sample corresponds to a Wi-Fi signal is also based onthe average slope value. For example, in Table 1, the average slopevalue of the slope values corresponding to frequency bins 1 to 6 thatare preceding the peak frequency bin 7 is (30+28+25+20+15)/5=23.6.

In some embodiments, the slope calculation module 306 also computes anaverage slope value of the slope values corresponding to the frequencybins subsequent to the peak frequency bin. In such embodiments,determining whether the FFT sample corresponds to a Wi-Fi signal is alsobased on the average slope value. For example, in Table 1, the averageslope value of the slope values corresponding to frequency bins 8 to 12that are subsequent to the peak frequency bin 7 is(20+25+30+15+25)/5=23.

In some embodiments, the slope calculation module 306 also computes afirst average slope value of the slope values corresponding to thefrequency bins preceding the peak frequency bin. The slope calculationmodule 306 further computes a second average slope value of the slopevalues corresponding to the frequency bins subsequent to the peakfrequency bin, and computes a third average slope value based on thefirst average slope value and the second average slope value. In suchembodiments, determining whether the FFT sample corresponds to a Wi-Fisignal is also based on the third average slope value, for example,(23.6+23)/2=23.3.

The sub-peak bin estimation module 308 can be software includingroutines for determining a signal type for the signal based on thenumber of sub-peak frequency bins within the particular number offrequency bins from the peak frequency bin. In some embodiments, thesub-peak bin estimation module 308 can be a set of instructionsexecutable by the processor 204 to provide the functionality describedherein. In some other embodiments, the sub-peak bin estimation module308 can be stored in the memory 206 of the Wi-Fi signature detectionapplication 208 and can be accessible and executable by the processor204.

In some embodiments, the sub-peak bin estimation module 308 determines asignal type for the signal based on the number of sub-peak frequencybins within the particular number of frequency bins from the peakfrequency bin. In some embodiments, the sub-peak bin estimation module308 identifies a peak frequency bin from a plurality of frequency binsfor an FFT sample corresponding to signal strength for a signal detectedwithin a frequency channel at a particular time. In some embodiments,the peak frequency bin corresponds to a peak in the signal strength forthe signal. The sub-peak bin estimation module 308 then determines anumber of sub-peak frequency bins within a particular number offrequency bins from the peak frequency bin.

In some embodiments, the sub-peak frequency bin is any frequency bincorresponding to a signal strength that is (a) lower than the peaksignal strength, (b) higher than at least the signal strength for nconsecutive frequency bins in the plurality of frequency bins precedingthe particular bin, and (c) higher than at least the signal strength form consecutive frequency bins in the plurality of frequency binssubsequent to the particular bin. In the example illustrated in Table 1,frequency bin 11 corresponds to a sub-peak because the signal strengthlevel −65 dBm is (a) lower than the peak signal strength −50 dBm, (b)higher than at least 3 consecutive frequency bins in the plurality offrequency bins preceding the particular bin, and (c) higher than atleast the signal strength for 3 consecutive frequency bins in theplurality of frequency bins subsequent to the particular bin.

Finally, the sub-peak bin estimation module 308 determines a signal typefor the signal based at least on the number of sub-peak frequency binswithin the particular number of frequency bins from the peak frequencybin. For example, the FFT sample illustrated in Table 1 may beclassified as a non-Wi-Fi signal because there is only 1 sub-peakfrequency bin. On the other hand, according to some embodiments, if atleast two sub-peak bins are identified preceding the peak bin and atleast two sub-peak bins are identified subsequent to the peak bin, thecorresponding FFT sample will be classified as a Wi-Fi signal.

In some embodiments, the sub-peak bin estimation module 308 alsodetermines a burst duration for the signal. In such embodiments,determining the signal type for the signal is also based on the burstduration. In some embodiments, the signal type includes Wi-Fi signals aswell as non-Wi-Fi signals.

In some embodiments, determining the number of sub-peak frequency binsalso includes: identifying a plurality of first frequency bins withinthe particular number of frequency bins from the peak frequency bin;determining a rate of change between the signal strength correspondingto one of the plurality of first frequency bins and the signal strengthcorresponding to each of the n frequency bins immediately preceding theone of the first frequency bins; determining whether the rate of changeis positive; and determining that the one of the first frequency bins isa sub-peak bin in response to determining that the rate of change ispositive.

In other embodiments, determining the number of sub-peak frequency binsalso includes: identifying a plurality of first frequency bins withinthe particular number of frequency bins from the peak frequency bin;determining a number of rates of change between the signal strengthcorresponding to each of the plurality of first frequency bins and thesignal strength corresponding to the peak frequency bin; determining asatisfying rate of change from the number of rates of change; thesatisfying rate of change being less than any rates of change in thenumber of rages of change computed between at least one first frequencybin and the peak frequency bin, wherein the at least one first frequencybin is between the first frequency bin corresponding to the satisfyingrate of change and the peak bin; and determining that the firstfrequency bin corresponding to the satisfying rate of change is asub-peak frequency bin.

The burst measurement module 310 can be software including routines forestimating a duration of the wireless signal burst that is longer than afirst time period. In some embodiments, the burst measurement module 310can be a set of instructions executable by the processor 204 to providethe functionality described herein. In some other embodiments, the burstmeasurement module 310 can be stored in the memory 206 of the Wi-Fisignature detection application 208 and can be accessible and executableby the processor 204.

In some embodiments, the burst measurement module 310 estimates aduration of the wireless signal burst. In some embodiments, the burstmeasurement module 310 first obtains a first plurality of samplescorresponding to a first set of wireless signals received in a firsttime period from a first source. In some embodiments, the first set ofwireless signals corresponds to a portion of a wireless signal burstfrom the first source. In some embodiments, the burst measurement module310 then obtains a second plurality of samples corresponding to a secondset of wireless signals received in a second time period from a secondsource. Responsive to determining that the second set of wirelesssignals has a higher signal strength than the first set of wirelesssignals, the burst measurement module 310 then determines that the firstset of wireless signals corresponding to a portion of a wireless signalburst from the first source. Finally, the burst measurement module 310then estimates a duration of the wireless signal burst that is longerthan the first time period.

In some embodiments, determining that the second set of wireless signalshas a higher signal strength than the first set of wireless signalsincludes: computing a first average signal strength for the first set ofwireless signals; computing a second average signal strength for thesecond set of wireless signals; and comparing the first average signalstrength and the second average signal strength.

The classification module 312 can be software including routines forclassifying Wi-Fi signals. In some embodiments, the classificationmodule 312 can be a set of instructions executable by the processor 204to provide the functionality described herein. In some otherembodiments, the classification module 312 can be stored in the memory206 of the Wi-Fi signature detection application 208 and can beaccessible and executable by the processor 204.

In some embodiments, the classification module 312 determines that anFFT sample corresponds to a Wi-Fi signal based on analysis of anadjacent channel. In some embodiments, the classification module 312determines a usage of a first radio frequency channel related to Wi-Fiwireless signals. In some embodiments, the classification module 312then detects a wireless signal on a second radio frequency channeladjacent to the first radio frequency channel. In some embodiments, thewireless signal is near an edge of the second radio frequency channelshared with the first radio frequency channel. In some embodiments, theclassification module 312 then determines that wireless signal detectedon the second radio frequency channel corresponds to Wi-Fi wirelesssignals based at least on the usage of the first radio frequency channelrelated to Wi-Fi wireless signals.

In some embodiments, determining that wireless signal detected on thesecond radio frequency channel corresponds to Wi-Fi wireless signalsincludes: determining whether the usage of the first radio frequencychannel exceeds a particular threshold and determining that wirelesssignal detected on the second radio frequency channel corresponds toWi-Fi wireless signals in response to determining that the usage of thefirst radio frequency channel exceeds a particular threshold.

The characteristic matching module 314 can be software includingroutines for classifying Wi-Fi signals based on characteristic matching.In some embodiments, the characteristic matching module 314 can be a setof instructions executable by the processor 204 to provide thefunctionality described herein. In some other embodiments, thecharacteristic matching module 314 can be stored in the memory 206 ofthe Wi-Fi signature detection application 208 and can be accessible andexecutable by the processor 204.

In some embodiments, the characteristic matching module 314 determinesthat the FFT sample corresponds to a Wi-Fi signal based characteristicmatching. In some embodiments, the characteristic matching module 314detects a first wireless signal. In some embodiments, the characteristicmatching module 314 then determines that at least a portion of thecharacteristics associated with the first wireless signal matches thatof a second wireless signal that was previously classified as a Wi-Fisignal. Finally, the characteristic matching module 314 classifies thefirst wireless signal as a Wi-Fi signal based at least on thedetermination that at least a portion of the characteristics associatedwith the first wireless signal matches the second wireless signal.

In some embodiments, the portion of characteristics that matches that ofthe second wireless signal includes a frequency bin in which a peaksignal strength was detected. In some embodiments, the portion ofcharacteristics that matches that of the second wireless signal includesa highest signal strength. In some embodiments, the portion ofcharacteristics that matches that of the second wireless signal includesa frequency bin in which a peak signal strength was detected and ahighest signal strength.

The combination module 316 can be software including routines forclassifying Wi-Fi signals. In some embodiments, the combination module316 can be a set of instructions executable by the processor 204 toprovide the functionality described herein. In some other embodiments,the combination module 316 can be stored in the memory 206 of the Wi-Fisignature detection application 208 and can be accessible and executableby the processor 204.

In some embodiments, the combination module 316 detects a first wirelesssignal corresponding to a frequency band. In some embodiments, thecombination module 316 then identifies different subsections of thefrequency band and corresponding component wireless signals in thedifferent subsections. In some embodiments, the component wirelesssignals form the first wireless signal. In some embodiments, thecombination module 316 then selects a plurality of combinations ofcomponent wireless signals using the different subsections andclassifies the plurality of combinations of component wireless signalsas Wi-Fi signals or non-Wi-Fi signals. Finally, the combination module316 determines that the first wireless signal is non-Wi-Fi in responseto determining that none of the plurality of combinations of componentwireless signals has been classified as Wi-Fi.

Processes for Detecting Wi-Fi Signatures from FFT Samples

FIG. 4 illustrates an example process 400 for detecting Wi-Fi signalsfrom FFT samples according to embodiments of the present disclosure.Process 400 begins with FFT samples being divided into frequency blocks(one or more operations indicated by block 402). Bandwidth is thendetermined for the FFT sample (one or more operations indicated by block404). A determination is made as to whether the FFT sample correspondsto a narrowband signal (one or more operations indicated by decisionblock 406).

If it is determined that the FFT sample does not correspond to anarrowband signal (406—No), then channel utilization is calculated basedon a determination that the FFT sample corresponds to a Wi-Fi signal(one or more operations indicated by block 410). If it is determinedthat the sample corresponds to a narrowband signal (406—Yes), adetermination whether the FFT sample corresponds to a Wi-Fi signal ismade based on certain criteria (one or more operations indicated byblock 408). FIGS. 5, 6, 9, 10 and 11 illustrates example processes 408for determining whether the FFT sample corresponds to a Wi-Fi signalbased on various criteria. More details describing this example ofprocess 408 will be described with regard to the descriptions of FIGS.5, 6, 9, 10 and 11.

FIG. 5 illustrates an example process 408 for detecting a Wi-Fi signal.This process 408 as illustrated in FIG. 5 detects Wi-Fi signals based onslope values according to embodiments of the present disclosure. Duringoperation, the process 408 as illustrated in FIG. 5 determines whetherthe FFT sample corresponds to a Wi-Fi signal based on the slope values.In some embodiments, the process 400 is performed by the slopecalculation module 306. The process 400 begins when a peak frequency binfor an FFT sample is identified from a plurality of frequency binscorresponding to signal strength for a signal detected on a channel at aparticular time (one or more operations indicated by block 504). In someembodiments, the peak frequency bin corresponds to a peak in signalstrength. A set of slope values between the signal strengthcorresponding to the peak frequency bin and the signal strength for eachof a plurality of frequency bins within a certain range from the peakfrequency bin is then computed (one or more operations indicated byblock 506). In some embodiments, this is performed by the slopecalculation module 306. Each of the slope values is compared to acorresponding threshold value that is dependent on the number of thefrequency bins between the peak frequency bin and the frequency bincorresponding to that slope (one or more operations indicated by block508). A number of satisfying slope values is determined from the set ofslope values (one or more operations indicated by block 510). In someembodiments, the satisfying slope values fall within their correspondingthresholds. Finally, determines whether the FFT sample corresponds to aWi-Fi signal based at least on the number of satisfying slope values(one or more operations indicated by block 514).

In some embodiments, a burst duration for the signal is determined (oneor more operations indicated by block 512). In such embodiments,determining whether the FFT sample corresponds to a Wi-Fi signal is alsobased on the burst duration.

FIG. 6 illustrates an example process 408 for detecting a Wi-Fi signaland determining signal type. This process 408 as illustrated FIG. 6 indetects a Wi-Fi signal and determines signal type based on a number ofsub-peak frequency bins according to embodiments of the presentdisclosure. In some embodiments, the sub-peak bin estimation module 308performs the process 408, which determines a signal type for the signalbased on the number of sub-peak frequency bins within the particularnumber of frequency bins from the peak frequency bin. The process 408 asillustrated FIG. 6 begins with a peak frequency bin being identifiedfrom a plurality of frequency bins for an FFT sample corresponding tosignal strength for a signal detected within a frequency channel at aparticular time (one or more operations indicated by block 602). In someembodiments, the peak frequency bin corresponds to a peak in the signalstrength for the signal. A number of sub-peak frequency bins within aparticular number of frequency bins from the peak frequency bin isdetermined (one or more operations indicated by block 604). Finally, asignal type for the signal based at least on the number of sub-peakfrequency bins within the particular number of frequency bins from thepeak frequency bin is determined (one or more operations indicated byblock 608).

In some embodiments, a burst duration for the signal is also determined(one or more operations indicated by block 606). In such embodiments,determining the signal type for the signal is also based on the burstduration. In some embodiments, the signal type includes Wi-Fi signals aswell as non-Wi-Fi signals.

A previously mentioned, in some embodiments, the sub-peak frequency binis any frequency bin corresponding to a signal strengths that is (a)lower than the first signal strength, (b) higher than at least thesignal strength for n consecutive frequency bins in the plurality offrequency bins preceding the particular bin, and (c) higher than atleast the signal strength for m consecutive frequency bins in theplurality of frequency bins subsequent to the particular bin.

Determining a number of sub-peak bins may be performed in various ways.FIGS. 7A-7C illustrate an example process 604 for determining a numberof sub-peak bins according to embodiments of the present disclosure.

FIG. 7A illustrates an example process 604 for determining a number ofsub-peak bins according to some embodiments of the present disclosure.The process 604 as illustrated in FIG. 7A begins as a plurality offrequency bins within a particular range from the peak bin is identified(one or more operations indicated by block 702). A signal strengthcorresponding to each of the plurality of frequency bins is determined(one or more operations indicated by block 704). A determination is madeas to whether the signal strength is lower than a first signal strength(one or more operations indicated by decision block 706). If the signalstrength is not lower than a first signal strength (706—No), the process604 reverts to the one or more operations indicated by block 704. If thesignal strength is lower than a first signal strength (706—Yes), then adetermination is made as to whether the signal strength is higher thanat least the signal strength for n consecutive frequency bins in theplurality of frequency bins preceding the particular bin (one or moreoperations indicated by decision block 708). If the signal strength isnot higher than at least the signal strength for n consecutive frequencybins in the plurality of frequency bins preceding the particular bin(708—No), the process 604 reverts to the one or more operationsindicated by block 704. If the signal strength is higher than at leastthe signal strength for n consecutive frequency bins in the plurality offrequency bins preceding the particular bin (708-Yes), then adetermination is made as to whether higher than at least the signalstrength for m consecutive frequency bins in the plurality of frequencybins subsequent to the particular bin (one or more operations indicatedby decision block 710). If the signal strength is not higher than atleast the signal strength for m consecutive frequency bins in theplurality of frequency bins subsequent to the particular bin (710—No),the process 604 reverts to the one or more operations indicated by block704. If the signal strength is higher than at least the signal strengthfor m consecutive frequency bins in the plurality of frequency binssubsequent to the particular bin (710—Yes), a determination is made thatthe first bin is a sub-peak bin (one or more operations indicated byblock 712). The process is then repeated for each of the plurality ofthe first bins to determine a number of sub-peak bins (one or moreoperations indicated by block 714).

FIG. 7B illustrates an example process 604 for a number of sub-peak binsaccording to other embodiments of the present disclosure. The process604 as illustrated in FIG. 7B begins as a plurality of frequency binswithin a particular range from the peak bin is identified (one or moreoperations indicated by block 732). A rate of change between each of theplurality of the frequency bins and its preceding bins is determined(one or more operations indicated by block 734). A determination is madeas to whether the rate of change is positive (one or more operationsindicated by decision block 736). If the rate of change is not positive(736—No), the process reverts to the one or more operations indicated byblock 734. If the rate of change is positive (736—Yes), a determinationis made that the first bin in the plurality of frequency bins is asub-peak bin (one or more operations indicated by block 738). Theprocess is then repeated for each of the plurality of the frequency binsto determine a number of sub-peak bins (one or more operations indicatedby block 740).

FIG. 7C illustrates an example process for a number of sub-peak binsaccording to yet other embodiments of the present disclosure. Theprocess 604 as illustrated in FIG. 7C begins as a plurality of frequencybins within a particular range from the peak bin is identified (one ormore operations indicated by block 752). A rate of change between eachof the plurality of the frequency bins and the peak bin is determined(one or more operations indicated by block 754). A determination is madeas to whether the rate of change is less than any rates of changecomputed between at least one bin and the peak bin where the at leastone bin is between the first bin and the peak bin (one or moreoperations indicated by block 756). If the rate of change is not lessthan any rates of change computed between at least one bin and the peakbin where the at least one bin is between the first bin and the peak bin(756—No), then the process reverts to the one or more operationsindicated by block 754. If the rate of change is less than any rates ofchange computed between at least one bin and the peak bin where the atleast one bin is between the first bin and the peak bin (756—Yes), thena determination is made that the first bin is a sub-peak bin (one ormore operations indicated by block 758). The process is then repeatedfor each of the plurality of the first bins to determine a number ofsub-peak bins (one or more operations indicated by block 760).

FIG. 8 illustrates an example process 800 for estimating a burst sizeaccording to embodiments of the present disclosure. The process 800begins as a first plurality of samples corresponding to a first set ofwireless signals received in a first time period from a first source isobtained (one or more operations indicated by block 802). In someembodiments, the first set of wireless signals corresponding to aportion of a wireless signal burst from the first source. A secondplurality of samples corresponding to a second set of wireless signalsreceived in a second time period from a second source is obtained (oneor more operations indicated by block 804). A determination is made asto whether the second set of wireless signals has a higher signalstrength than the first set of wireless signals (one or more operationsindicated by block 806). It is then determined that the first set ofwireless signals corresponds to a portion of a wireless signal burstfrom the first source (one or more operations indicated by block 808).In some embodiments this determination is based on the determinationthat the second set of wireless signals has a higher signal strengththan the first set of wireless signals. A duration of the wirelesssignal burst that is longer than the first time period is estimated (oneor more operations indicated by block 810).

In some embodiments, determining that the second set of wireless signalshave a higher signal strength than the first set of wireless signalsincludes: computing a first average signal strength for the first set ofwireless signals; computing a second average signal strength for thesecond set of wireless signals and comparing the first average signalstrength and the second average signal strength.

FIG. 9 illustrates an example process 408 for detecting Wi-Fi signalsbased on estimation for adjacent channels according to embodiments ofthe present disclosure. The process 408 as illustrated in FIG. 9 beginsas a usage of a first radio frequency channel related to Wi-Fi wirelesssignals is determined (one or more operations indicated by block 902).Note that, usage of a radio frequency channel generally refers to one ormore of channel utilization and/or duty cycle. Optionally, in someembodiments, whether the usage of the first radio frequency channelexceeds a particular threshold is determined (one or more operationsindicated by block 904). A wireless signal on a second radio frequencychannel adjacent to the first radio frequency channel is detected (oneor more operations indicated by block 906). In some embodiments, thewireless signal being is an edge of the second radio frequency channelshared with the first radio frequency channel. A determination is madethat wireless signal detected on the second radio frequency channelcorresponds to Wi-Fi wireless signals based at least on the usage of thefirst radio frequency channel related to Wi-Fi wireless signals (one ormore operations indicated by block 908).

FIG. 10 illustrates an example process 408 for classifying Wi-Fi signalsbased on characteristic matching according to embodiments of the presentdisclosure. The process 408 as illustrated in FIG. 10 begins as a firstwireless signal is detected (one or more operations indicated by block1002). A determination is made that at least a portion of thecharacteristics associated with the first wireless signal matches thatof a second wireless signal that was previously classified as a Wi-Fisignal (one or more operations indicated by block 1004). The firstwireless signal is classified as a Wi-Fi signal based at least on thedetermination that at least a portion of the characteristics associatedwith the first wireless signal matches the second wireless signal (oneor more operations indicated by block 1006).

FIG. 11 illustrates an example process 408 for classifying Wi-Fi signalsaccording to other embodiments of the present disclosure. The process408 as illustrated in FIG. 11 begins as a plurality of wireless signalson a corresponding plurality of frequency channels is detected (one ormore operations indicated by block 1102). Each of the plurality ofwireless signals is classified as Wi-Fi signals or non-Wi-Fi signals(one or more operations indicated by block 1104). Information for thewireless signals from the plurality of wireless signals that wereclassified as Wi-Fi signals is analyzed to identify at least two of thewireless signals detected on two corresponding channels as a portion ofa same Wi-Fi transmission from a same source device (one or moreoperations indicated by block 1106). In some embodiments, a channelwidth of each of the plurality of frequency channels is 20 Mhz. In someembodiments, identifying at least two of the wireless signals as aportion of the same Wi-Fi transmission includes determining that the atleast two wireless signals are detected with a same signal strengthrange. In some embodiments, identifying at least two of the wirelesssignals as a portion of the same WiFi transmission includes determiningthat the at least two wireless signals are detected within a same timeperiod.

The present disclosure may be realized in hardware, software, or acombination of hardware and software. The present disclosure may berealized in a centralized fashion in one computer system or in adistributed fashion where different elements are spread across severalinterconnected computer systems coupled to a network. A typicalcombination of hardware and software may be an access point with acomputer program that, when being loaded and executed, controls thedevice such that it carries out the methods described herein.

The present disclosure also may be embedded in non-transitory fashion ina computer-readable storage medium (e.g., a programmable circuit; asemiconductor memory such as a volatile memory such as random accessmemory “RAM,” or non-volatile memory such as read-only memory,power-backed RAM, flash memory, phase-change memory or the like; a harddisk drive; an optical disc drive; or any connector for receiving aportable memory device such as a Universal Serial Bus “USB” flashdrive), which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

As used herein, “digital device” generally includes a device that isadapted to transmit and/or receive signaling and to process informationwithin such signaling such as a station (e.g., any data processingequipment such as a computer, cellular phone, personal digitalassistant, tablet devices, etc.), an access point, data transfer devices(such as network switches, routers, controllers, etc.) or the like.

As used herein, “access point” (AP) generally refers to receiving pointsfor any known or convenient wireless access technology which may laterbecome known. Specifically, the term AP is not intended to be limited toIEEE 802.11-based APs. APs generally function as an electronic devicethat is adapted to allow wireless devices to connect to a wired networkvia various communications standards.

As used herein, the term “interconnect” or used descriptively as“interconnected” is generally defined as a communication pathwayestablished over an information-carrying medium. The “interconnect” maybe a wired interconnect, wherein the medium is a physical medium (e.g.,electrical wire, optical fiber, cable, bus traces, etc.), a wirelessinterconnect (e.g., air in combination with wireless signalingtechnology) or a combination of these technologies.

As used herein, “information” is generally defined as data, address,control, management (e.g., statistics) or any combination thereof. Fortransmission, information may be transmitted as a message, namely acollection of bits in a predetermined format. One type of message,namely a wireless message, includes a header and payload data having apredetermined number of bits of information. The wireless message may beplaced in a format as one or more packets, frames or cells.

As used herein, “wireless local area network” (WLAN) generally refers toa communications network links two or more devices using some wirelessdistribution method (for example, spread-spectrum or orthogonalfrequency-division multiplexing radio), and usually providing aconnection through an access point to the Internet; and thus, providingusers with the mobility to move around within a local coverage area andstill stay connected to the network.

As used herein, the term “mechanism” generally refers to a component ofa system or device to serve one or more functions, including but notlimited to, software components, electronic components, electricalcomponents, mechanical components, electro-mechanical components, etc.

As used herein, the term “embodiment” generally refers an embodimentthat serves to illustrate by way of example but not limitation.

Some portions of the detailed descriptions are presented in terms ofalgorithms and symbolic representations of operations on data bitswithin a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise as apparent from the foregoing discussion,it is appreciated that throughout the description, discussions utilizingterms including “processing” or “computing” or “calculating” or“determining” or “displaying” or the like, refer to the action andprocesses of a computer system, or similar electronic computing device,that manipulates and transforms data represented as physical(electronic) quantities within the computer system's registers andmemories into other data similarly represented as physical quantitieswithin the computer system memories or registers or other suchinformation storage, transmission or display devices.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, etc.) can be coupled to the system eitherdirectly or through intervening I/O controllers.

The particular naming and division of the modules, routines, features,attributes, methodologies and other aspects are not mandatory orsignificant, and the mechanisms that implement the specification or itsfeatures may have different names, divisions and/or formats.Furthermore, as will be apparent to one of ordinary skill in therelevant art, the modules, routines, features, attributes, methodologiesand other aspects of the disclosure can be implemented as software,hardware, firmware or any combination of the three. Also, wherever acomponent, an example of which is a module, of the specification isimplemented as software, the component can be implemented as astandalone program, as part of a larger program, as a plurality ofseparate programs, as a statically or dynamically linked library, as akernel loadable module, as a device driver, and/or in every and anyother way known now or in the future to those of ordinary skill in theart of computer programming.

It will be appreciated to those skilled in the art that the precedingexamples and embodiments are example and not limiting to the scope ofthe present disclosure. It is intended that all permutations,enhancements, equivalents, and improvements thereto that are apparent tothose skilled in the art upon a reading of the specification and a studyof the drawings are included within the true spirit and scope of thepresent disclosure. It is therefore intended that the following appendedclaims include all such modifications, permutations and equivalents asfall within the true spirit and scope of the present disclosure.

While the present disclosure has been described in terms of variousembodiments, the present disclosure should not be limited to only thoseembodiments described, but can be practiced with modification andalteration within the spirit and scope of the appended claims. Likewise,where a reference to a standard is made in the present disclosure, thereference is generally made to the current version of the standard asapplicable to the disclosed technology area. However, the describedembodiments may be practiced under subsequent development of thestandard within the spirit and scope of the description and appendedclaims. The description is thus to be regarded as illustrative ratherthan limiting.

What is claimed is:
 1. A non-transitory computer readable mediumcomprising instructions which, when executed by one or more hardwareprocessors, causes performance of operations comprising: determiningwhen a difference between signal strengths of a first wireless signalreceived in a first time period and a second wireless signal received ina second time period is greater than a threshold; determining when thefirst wireless signal is transmitted from a first source and when thesecond wireless signal is transmitted from a second source; determininga signal strength of a third wireless signal from samples correspondingto the third wireless signal received in a third time period;determining when a difference between the signal strength of the firstwireless signal and the signal strength of the third wireless signal isless than the threshold; and estimating when a duration of a wirelesssignal burst from the first source is longer than the first time period.2. The computer readable medium of claim 1, comprising instructionswhich, when executed by one or more hardware processors, causesperformance of operations comprising determining when a first set ofwireless signals has a higher signal strength than a second set ofwireless signals.
 3. The computer readable medium of claim 2, whereindetermining when the first set of wireless signals has a higher signalstrength than the second set of wireless signals includes: determining afirst average signal strength for a plurality of wireless signalscorresponding to the first set of wireless signals; determining a secondaverage signal strength for a plurality of wireless signalscorresponding to the second set of wireless signals; and comparing thefirst average signal strength the second average signal strength.
 4. Thecomputer readable medium of claim 1, further comprising instructionswhich, when executed by one or more hardware processors, causesperformance of operations comprising: determining that a characteristicassociated with the first wireless signal matches that of the thirdwireless signal, wherein the third wireless signal was previouslyclassified as a Wi-Fi signal; and classifying the first wireless signalas a Wi-Fi signal based on the determination that the characteristicassociated with the first wireless signal matches that of the thirdwireless signal.
 5. A computing device, comprising: one or moreprocessors; and a memory having instructions stored thereon, which whenexecuted by the one or more processors, cause the computing device toperform operations including: generating a plurality of frequency binsfor received wireless signals based on a time period for each of thereceived wireless signals; identifying a peak frequency bin from theplurality of frequency bins based on a signal strength of receivedwireless signals within the plurality of frequency bins; determining aslope value based on a decrease in signal strength between the peakfrequency bin and a different frequency bin from the plurality offrequency bins; comparing the slope value to a threshold value; anddetermining whether the received wireless signals correspond to a Wi-Fisignal based on the comparison.
 6. The computing device of claim 5,wherein the received wireless signals are determined to be Wi-Fi signalswhen the slope value is greater than the threshold value.
 7. Thecomputing device of claim 5, wherein the received wireless signals aredetermined to be narrow band interference signals when the slope valueis less than the threshold value.
 8. The computing device of claim 5,wherein the slope value is an average slope value of a plurality ofslope values.
 9. The computing device of claim 8, wherein the averageslope value includes frequency bins that precede the peak frequency bin.10. The computing device of claim 8, wherein the average slope valueincludes frequency bins that are subsequent to the peak frequency bin.